1. Field of the Invention
This invention relates to a photographic operation control circuit for a camera.
2. Description of the Prior Art
In recent years, the trend in photography has been to construct cameras so they permit fully automatic control of a sequence of photographic steps such as focusing, exposure setting, data printing, and film winding, simply by pushing down the release button. These conventional cameras, because they employ a sequence control system in an electrical circuit have a disadvantage of increasing the complexity of the circuitry. Further, since the electrical energy necessary to perform each cyclical exposure larger than in simpler cameras, the battery voltage may fall below the satisfactory operating level during one of the sequence of steps and result in faulty operation. That is, because the light sensor, exposure determining means and the shutter cocking and film winding mechanism must operate in sequence, it is quite possible that even though the battery voltage was at a satisfactory operating level before actuation of the release button, it may no longer be satisfactory after termination of the exposure setting step. In such a case, the following shutter cocking and film winding steps may stop before their completion and the camera may not be ready for the next exposure. The provision of so many successive steps in the camera gives rise to an additional problem that the mere transition from one step to another may not always be reliable. For example, the shutter may operate before the focusing operation has been completed, and this would result in unfocused photographs.
For this reason, auto-focus cameras are generally provided with means responsive to a setting completion signal for permitting a transition to the subsequent step of making an exposure. However, in a camera which only measures the distance automatically and the objective lens is adjusted manually, it is impossible to detect the completion of the actual setting of the objective lens so that when a release is actuated during the focusing operation, the immediately subsequent exposure may result in an out-of-focus image on the film. Moreover, when ever-varying data such as the time from a digital clock are printed, provision must be made for latching the presentation of the data for the period of actuation of the data recorder, or otherwise two or more successive different data would be recorded as overlapping one another, thus effecting an ambiguous recording of data. In this connection, it should be noted that the data to be printed, is preferably the data at the time of photographing, but not of the one occurring when the presentation of the data is latched. A camera having so many types of functions is required not only to display information of the exposure factors and value, but also to indicate various data such as the focusing condition and data to be recorded so that the structure of the indicator is complicated.